Melatonin supplements may help treat sleep conditions like insomnia, as well as post-traumatic brain injuries and migraines. They’re generally safe and nontoxic.
However, taking more than you need may raise the risk of side effects. While it is technically possible to overdose on melatonin, life-threatening reactions are rare.
Melatonin supplements are safe when used in moderate doses—less than 5 milligrams—for short periods. Taking too much or using it longer than recommended can increase the risk of side effects from melatonin, such as:
- Headache
- Fatigue
- Dizziness
- Upset stomach
- Vivid dreams or nightmares
- Bedwetting (in children)
- Rash
- Fractures (in older adults)
In rare cases, some people may experience allergic reactions or other effects on bodily processes when taking melatonin, such as changes in blood pressure, blood sugar, and seizure threshold (how easily a person may have a seizure). This is why you should consider speaking to a healthcare provider before using this supplement.
Melatonin can also interfere with some medications, such as:
- Blood thinners like Coumadin (warfarin)
- Antidepressants like Luvox (fluvoxamine)
- Antibiotics like Cipro (ciprofloxacin)
- Caffeine
- Oral birth control
- Immunosuppressants (drugs that lower your immune system activity)
- Alcohol
- Other sleep aid supplements, such as kava, valerian, or L-tryptophan
More research is needed to better understand how melatonin can affect you in the long term. Some research suggests that long-term melatonin use may reduce semen quality. It’s best to use melatonin only for a short period, except when otherwise recommended by your healthcare provider.
There’s no well-defined standard dose for melatonin. However, different studies have used melatonin doses between 0.1 and 10 milligrams.
Experts consider low to moderate doses of melatonin, between 5 and 6 milligrams, to be a safe and effective daily amount. Doses as low as 1 milligram can actually be just as effective as higher amounts and may reduce the risk of overdosing. For best results, melatonin should be taken 30-60 minutes before bedtime.
The recommended doses for different ages include:
- Infants (under 2): 1 milligram (mg)
- Children (2-9): 2.5-3 mg
- Adolescents (10–17 years): 5 mg
- Adults (18+): 5-6 mg
- Children with special needs: 0.5-10 mg
Some studies found that taking melatonin at doses higher than 10 milligrams increases the risk of side effects. The amount of melatonin in each supplement can vary widely, making it easier to take too much. Some supplements may even contain as much as 478% more melatonin than the amount listed on the label.
This is why it’s best to stick to the dose and brand recommended by your healthcare provider or pharmacist (a health professional trained in preparing and giving out prescription drugs). It’s also important to make sure your melatonin has safe ingredients and is only purchased from manufacturers that have been third-party tested.
Taking too much melatonin can lead to increased side effects, such as:
- Excessive sleepiness
- Upset stomach
- Dizziness
- Fatigue
- Confusion
- Increased heart rate
- Skin irritation
- Hypothermia (low body temperature, typically below 95 degrees Fahrenheit)
If you notice any of these side effects, you may want to discontinue melatonin and get expert advice on the optimal dose for you. Most side effects resolve after discontinuing melatonin.
Melatonin overdose can also cause serious symptoms that require urgent medical attention:
- Difficulty breathing
- Seizures
- Chest pain
- Tremors
- Rise in blood pressure
Melatonin affects people differently, depending on their age, dose, and underlying conditions. For example, using doses as low as 3 milligrams has been associated with an increased risk of fractures in older adults.
If you want to take more than 10 milligrams of melatonin or use it for longer than six months, do not do so without first talking to your healthcare provider.
A melatonin overdose isn’t usually life-threatening. If you suspect symptoms of melatonin overdose, you should stop taking melatonin and seek medical care. Healthcare professionals will determine the severity of your symptoms and advise you on the next step.
If your child or loved one has irregular breathing or loses consciousness after taking melatonin, seek immediate emergency care.
Melatonin has low toxicity and is generally safe. However, taking more than recommended or using it for a long time can increase your risk of side effects. Common symptoms of melatonin overdose include excessive sleepiness, stomach upset, dizziness, confusion, and increased heart rate.
You may also experience serious symptoms of melatonin overdose, like seizures, difficulty breathing, chest pain, or increased blood pressure. If you notice any of these symptoms, call Poison Control immediately.
